SF6, HFCs or PFCs is known to have a higher earth warming index and a longer life span and is designated as six representative earth warming gases along with CO2, CH4 and N2O. In particular, SF6 has the highest earth warming impact level among six representative earth warming gases and has 23,900 times higher earth warming index as compared to CO2 which is one of representative earth warming gases. So, SF6 is the worst environment pollutant.
In addition, all countries including advanced countries as well as developing countries are included in the group for greenhouse gas emission cut countries after 2013 in accordance with the weather protocol which was adapted in the 13th UNFCCC(United Nations Framework Convention on Climate Change) on Dec. 15, 2007. Korea will be a member of the duty reduction countries in 2013, so a greenhouse gas reduction should be implemented. It is urgent that an economic and efficient measure for a separation and recovery of SF6, which causes a serious greenhouse gas effect, should be sought and set.
In a conventional method for a separation, purification and recovery of all kinds of gases including fluoro-gases of SF6, HFCs and PFCs, all mixed gases are liquified and distilled depending on their boiling points and are used.
Since the liquification temperatures of gases are very low, there are a lot of difficulties for liquification, and a lot of energy is needed. So, a low energy consumption process is being developed in a process of separating a specific component from multi-component mixed gases.
For example, the US patent gazette 2002/0062734 discloses a method of separating nitrogen and SF6 using a membrane separation method.